The present invention relates to the use of the complexes formed by metallic salts of aliphatic carboxylic acids or metallic chelate 1,3-dione compounds with alkyl-substituted diamines or alkyl-substituted triamines as catalysts to impart hypergolicity (i.e. self-ignition) to a wide variety of both polar (i.e. alcohols) and non-polar (i.e. octane, decane, kerosene) organic fuels when rocket-grade hydrogen peroxide is employed as an oxidizer. The alkyl substituted diamines and alkyl-substituted triamines are integral constituents of the catalyst at the molecular level. If the amines are employed in stoichiometric excess, however, they can additionally serve as either promoters or co-solvents (phase-joiners).
U.S. Pat. No. 5,932,837 to Rusek discloses catalyst systems suitable for use with polar organic fuels that are miscible with hydrogen peroxide such as low molecular weight alcohols or ketones. The catalyst system consists of an amine or amide to function as a “propagator” (i.e. as a promoter) and a metal salt such as a metal acetate that decomposes in solution to form a metallic oxide with the desired catalytic activity capable of rendering the fuel hypergolic with rocket-grade hydrogen peroxide. Rusek teaches the use of amines selected from the group comprising urea, formamide, acetamide, ethylenediaminetetraacetic acid (‘EDTA’) or base-substituted EDTA. The catalyst systems described by Rusek form “microdispersed colloidal” metallic oxides in situ. However, these insoluble particles have the undesirable property of coagulating or precipitating over time. Moreover, they cannot be prepared in non-polar organic fuels in which the precursor metal salt is insoluble.
Eric Hurlbert et al. in “Nontoxic Orbital Maneuvering and Reaction Control Systems for Reusable Spacecraft” Journal of Propulsion and Power, Vol. 14, No. 5 (1998) have previously described the use of unspecified amounts of tetramethylethylenediamine (“TMEDA”) as a “promoter” in conjunction with catalysts consisting of the dodecyl benzenesulfonic acid and other aromatic hydrocarbon sulfonic acid salts of cobalt, chromium, copper, and iron to catalyze the decomposition of hydrogen peroxide, therby imparting hypergolicity to kerosene and other non-polar organic fuels. Cobalt, chromium, copper, and iron salts of dodecyl benzenesulfonic acid and mixed dodecyl benzenesulfonic acid salts of these metals and other “long carbon chain” aromatic acids were selected by the authors of this paper because they are appreciably soluble in kerosene and other non-polar hydrocarbon fuels, i.e. “fuel-soluble.”
The authors of the aforementioned paper allege: “The catalyst, the promoter, and the complex formed by them must all be soluble in kerosene to make the fuel homogenous.” However, both the metallic salts of the aliphatic carboxylic acids and the metallic aliphatic carboxylate-amine complexes of the present invention are insoluble or only very sparingly soluble in kerosene and other non-polar organic compounds, yet they are capable of forming homogeneous mixtures in kerosene and other non-polar organic compounds (i.e. octane, decane, etc . . . ) if TMEDA or other amines, alcohols, acetylenic compounds, or other polar organic compounds are employed as co-solvents or phase-joiners.
A variety of organometallic compounds that are soluble in hydrocarbons (i.e. methylcyclopentadienylmanganese tricarbonyl, manganese (II) 2-ethylhexanoate, and dicylopentadienyl iron or “ferrocene”) were evaluated by the authors of the present invention in conjunction with TMEDA and other amines for their ability to catalyze the decomposition of hydrogen peroxide and to render both polar and non-polar liquid organic fuels hypergolic. The fact that these combinations did not prove to be effective demonstrates that the solubility of the metallic species in hydrocarbons is not a critical factor.